1. Technical Field of the Invention
The present invention relates to a rapid prototyping method and apparatus using V-CAD data, which can store entity data combining a shape and a physical property with a small storage capacity.
2. Description of the Related Art
The rapid prototyping is also referred to as a photo-solidification modeling method or stereolithography, and generally creates a three-dimensional object by solidifying a photo-curing resin with light.
FIGS. 1A to 1D are principle views of the rapid prototyping. (A) data of a three-dimensional model 1 produced by three-dimensional CAD or X-ray CT is horizontally sliced by a computer in order to generate cross-sectional shape data. (B) a liquid surface of a liquid photo-curing resin 2 is irradiated with a scanning laser beam 3 along slice data. The photo-curing resin is cured in such a manner that only a part irradiated with the laser beam has a given thickness. In this manner, a solidified layer 4 according to the cross-sectional shape data is formed. (C) Then, a table 5 having the solidified layer 4 (shaped object) mounted thereon is moved by only a distance corresponding to a pitch with which the model 1 was sliced, and an uncured thin resin layer is formed on the upper surface of the solidified layer. At this moment, a flattening operation called recoat is usually performed by using a member called a blade, and the surface of the uncured resin liquid is evenly smoothed. Subsequently, the surface is likewise irradiated with the scanning laser beam 3 according to the cross-sectional shape, and the solidified layer is united with the preceding solidified layer 4. (D) By repeating the steps B and C, the target three-dimensional model is created.
The above-described rapid prototyping is characterized in that a three-dimensional object can be created from the CAD data without using a mold, and used in many fields such as production of a master model for precision casting or the like, manufacture of a map or a stereo object and others.
However, the above-described conventional rapid prototyping has a problem that not only steps on the surface of a finished three-dimensional object become large when a slice pitch of the model is roughened but production requires more than several days. Further, on the contrary, when the slice pitch is set small and the solidified layer per one process is thinned in order to increase the precision of the object to be created, not only a program for the rapid prototyping is complicated but introducing of the uncured liquid becomes difficult due to surface tension, and the recoating time becomes long or a remaining surface of recoat is generated.